[PLUG] USB 3.0 ports stopped working

[American Citizen]

I have a Hewlett Packard Z420 workstation. About a week ago, the USB 
ports stopped working. Tonight I identified that it is the USB 3.0 ports 
that are not working, the USB 2.0 is still working just fine.

Has anyone had experience troubleshooting USB 3.0 ports under linux?
- Randall